Insight into the Nucleation Mechanism of p-Methoxybenzoic Acid in Ethanol-Water System from Metastable Zone Width

Abstract

The metastable zone width (MSZW) of p-methoxybenzoic acid (PMBA) in an ethanol-water system was measured using the polythermal method. The nucleation order m obtained by the Nývlt’s model indicates the nucleation of PMBA following a progressive nucleation mechanism at low saturation temperature (m = 3.18–7.50) and an instantaneous nucleation mechanism at high saturation temperature (m = 1.46–2.55). Then, combined with the metastable zone experiment and the Sangwal model, we found that the MSZW and the interfacial energy reached the maximum when the mass fraction of ethanol was 0.8, which resulted in the smallest crystal product size. Meanwhile, the maximum and obtained based on the modified Sangwal model indicating the PMBA needs to overcome a higher nucleation barrier in the ethanol mass fraction of 0.8. Finally, we proposed a preferential strategy for adjusting MSZW by correlating the interfacial energy with the change in ethanol mass fraction, saturation temperature, and cooling rate, respectively.

Metastable Zone Width and Primary Nucleation Kinetics for Crystallization of KCl from a KCl-MgCl2-H2O System

“…To further demonstrate the relationship between KCl solubility and temperature, two models were applied in this study to fit the experimental data. (22) where N denotes the number of experimental data points. As listed in Table 4 and Table 5, correlation coefficients R 2 of both models are greater than 0.997, and relative average deviations (RADs) are less than 10 −2 .…”

“…Determination of the metastable zone width includes two kinds of methods. One kind is to detect the change of nucleation amount, including laser meter, − turbidity meter, − visual inspection, FBRM, , and so on. The other is to monitor the change in solution physical properties with concentration, such as electrical conductivity, ultrasound velocity, , temperature, and so on.…”

Key Roles of Nucleation and Impurity Migration Behavior in Layer Melt Crystallization: Case Study of 4,5-Dimethyl-1,3-dioxol-2-one

“…Metastable zone width (MSZW) refers to the region between the solubility equilibrium curve and supersolubility curve, which is an important window − for the development of nucleation theory and the control of crystallization process. It was about 40 years ago that Nývlt proposed a semiempirical model based on classical nucleation theory (CNT) to describe the nucleation behavior of crystals, which has been widely used to estimate the MSZW.…”

Effects of Different Flotation Agents on the Nucleation and Growth of Potassium Chloride

“…To our knowledge, few researchers pay attention to the investigation of the primary nucleation of potassium chloride in the presence of flotation agents. As the initial stage of the crystallization process, nucleation directly affects the polymorph, purity, particle size, particle size distribution and other properties of crystal products, as well as the drying and transportation of subsequent products [13][14][15][16]. Therefore, three surfactants (ODA, DAH, SDS) commonly used for potassium chloride flotation were selected in this paper to study their effects on the nucleation behavior of potassium chloride, including both cationic and anionic surfactants, and the length of the hydrophobic carbon chain were also considered [17][18][19].…”